Chapter 16: Hypertension

I. Intensive care

1. Definition

   1. Blood pressure reference data in newborn infants are limited, but a systolic or diastolic blood pressure or a mean arterial blood pressure >95th percentile should be regarded as hypertension.

   2. Blood pressure increases over gestation and during the first days of life.

      1. Therefore, birthweight, gestational age, and postnatal age need to be taken into account when assessing blood pressure recordings.

      2. A term infant with a systolic blood pressure >90 mm Hg, a diastolic blood pressure >65 mm Hg, or a mean arterial pressure of >70 mm Hg should be regarded as hypertensive.

      3. Corresponding figures for very preterm infants (<32 weeks) are >75, >50, and >60 mm Hg.

2. Prevalence

   Hypertension is uncommon in early neonates.

   1. In a large study based on NICU admissions, 1% were coded with the diagnosis of hypertension.

3. Pathophysiology

   1. Blood pressure depends on cardiac function, vascular resistance, and sodium and water balance.

4. Risk factors

   1. Several factors and neonatal morbidities may contribute to blood pressure elevation, such as

      1. Fluid overload

      2. Renal disease

      3. Cardiovascular disorders including structural malformations

      4. Lung disease

      5. Endocrine/metabolic disturbances

   2. The use of umbilical artery catheters is associated with an increased risk of thromboembolism causing hypertension.

   3. Increased autonomic stress due to pain or discomfort is common in the infant undergoing intensive care, and may also lead to high blood pressure.

   4. Neurologic injury or seizures.

   5. Irritability (during assessment).

   6. Neonatal abstinence syndrome.

   7. Medications, including caffeine, theophylline, corticosteroids, vitamin D intoxication, inotropes, or certain maternal drugs.

5. Clinical presentation

   Hypertension is almost always detected due to routine monitoring of blood pressure, most accurately when measured invasively through umbilical or peripheral arterial catheter.

6. Diagnosis

   Hypertension should be defined as systolic/diastolic blood pressure above >95th percentile for gestational age and postnatal age, recorded on three separate occasions. It should be assessed when the infant is calm and with the appropriate-sized cuff, if not being measured invasively.

7. Management

   1. Nonpharmacological

      1. Optimizing nursing care and relieving stress, pain, and discomfort could reduce blood pressure.

   2. Pharmacological

      Published data on pharmacological therapy are limited.

      1. The severely hypertensive, symptomatic infant (usually blood pressure far above the 99th percentile, Table 16-1 should be treated in the NICU with intravenous administration of blood pressure–lowering drugs.

      2. It is important to monitor the blood pressure closely during pharmacologic treatment, preferably using an indwelling arterial line, and to avoid large and rapid reductions in BP.

      3. Severe, symptomatic hypertension should be treated, using calcium channel blockers as first line of treatment.

      4. ACE inhibitors reduce blood pressure in infants, but the risk of a drastic BP reduction should be considered due to the activation of the renin-angiotensin system during infancy.

      5. β-Blocking agents and nitroprusside have also been proven useful.

   3. Surgical

      Surgical treatment is only indicated if the underlying cause of hypertension is surgically treatable, eg, coarctation of the aorta or neoplasias.

8. Early developmental/therapeutic interventions

   1. Very preterm infants or babies with severe brain injuries, who are autonomically unstable, may benefit from a minimal stimulation environment.

   2. Sudden changes in blood pressure should be avoided in very preterm infants, ...